21534776640 has 560 divisors, whose sum is σ = 83149976448. Its totient is φ = 5280712704.

The previous prime is 21534776633. The next prime is 21534776671. The reversal of 21534776640 is 4667743512.

21534776640 is a `hidden beast` number, since 2 + 1 + 534 + 7 + 76 + 6 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 81881149 + ... + 81881411.

Almost surely, 2^21534776640 is an apocalyptic number.

21534776640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21534776640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41574988224).

21534776640 is an abundant number, since it is smaller than the sum of its proper divisors (61615199808).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21534776640 is an frugal number, since it uses more digits than its factorization.

21534776640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320 (or 286 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 45.

The spelling of 21534776640 in words is "twenty-one billion, five hundred thirty-four million, seven hundred seventy-six thousand, six hundred forty".